INFO: task syz-executor.4:16559 blocked for more than 140 seconds.
      Not tainted 4.4.174+ #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D ffff88009a3bf868 29616 16559   2109 0x00000004
 ffff88009a3bf868 ffff8800baaa17c0 a03bab38395b6cb1 ffff8800baaa17c0
 0000000000000001 ffff8800baaa2000 ffff8801db71f180 ffff8801db71f1a8
 ffff8801db71e898 ffff8800a594df00 ffff8800baaa17c0 ffffed0013477001
Call Trace:
 [<ffffffff82709b79>] schedule+0x99/0x1d0 kernel/sched/core.c:3355
 [<ffffffff8270a333>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3388
 [<ffffffff8270c492>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8270c492>] mutex_lock_nested+0x3c2/0xb80 kernel/locking/mutex.c:621
 [<ffffffff81492aa2>] do_truncate2+0x132/0x210 fs/open.c:61
 [<ffffffff814c7766>] handle_truncate fs/namei.c:2816 [inline]
 [<ffffffff814c7766>] do_last fs/namei.c:3286 [inline]
 [<ffffffff814c7766>] path_openat+0x2cf6/0x4470 fs/namei.c:3406
 [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495668>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff81495a17>] SYSC_open fs/open.c:1056 [inline]
 [<ffffffff81495a17>] SyS_open fs/open.c:1051 [inline]
 [<ffffffff81495a17>] SYSC_creat fs/open.c:1076 [inline]
 [<ffffffff81495a17>] SyS_creat+0x27/0x30 fs/open.c:1074
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
2 locks held by syz-executor.4/16559:
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff814fcd3f>] sb_start_write include/linux/fs.h:1517 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff814fcd3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff81492aa2>] do_truncate2+0x132/0x210 fs/open.c:61
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4
task: ffff8801da6f4740 task.stack: ffff8800001d0000
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:62 [inline]
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] flat_send_IPI_mask+0xf7/0x1b0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800001d7c88  EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300
RBP: ffff8800001d7cb8 R08: 0000000000000018 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000255a000 CR3: 00000001d8474000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34
 000000000001b6c0 0000000000000008 ffff8800001d7cd8 ffffffff81092bee
 0000000000000008 ffffffff82924260 ffff8800001d7d30 ffffffff81ab8252
Call Trace:
 [<ffffffff81092bee>] nmi_raise_cpu_backtrace+0x5e/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81ab8252>] nmi_trigger_all_cpu_backtrace.cold+0xa1/0xae lib/nmi_backtrace.c:85
 [<ffffffff81092ca4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff813b4762>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff813b4762>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813b4762>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813b4762>] watchdog.cold+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537
Code: 00 c3 5f ff 80 e6 10 75 e1 41 c1 e5 18 44 89 2c 25 10 c3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 c3 5f ff <41> f7 c4 00 02 00 00 75 1e 4c 89 e7 57 9d 0f 1f 44 00 00 e8 f1 
NMI backtrace for cpu 1
CPU: 1 PID: 16507 Comm: syz-executor.4 Not tainted 4.4.174+ #4
task: ffff8800a594df00 task.stack: ffff8800a1150000
RIP: 0010:[<ffffffff8115990e>]  [<ffffffff8115990e>] __preempt_count_sub arch/x86/include/asm/preempt.h:74 [inline]
RIP: 0010:[<ffffffff8115990e>]  [<ffffffff8115990e>] preempt_count_sub+0x5e/0x170 kernel/sched/core.c:3109
RSP: 0018:ffff8800a1157ba0  EFLAGS: 00000202
RAX: 0000000080000002 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff81b0abec RDI: 0000000000000001
RBP: ffff8800a1157ba8 R08: 0000000000000002 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff88009fd3763c R14: ffff8800a1157e44 R15: 0000000000000000
FS:  00007fa5a927a700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000002558308 CR3: 00000001d453a000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000002 ffff8800a1157bd0 ffffffff81242fa2 ffffffff8123d925
 ffffffff82fb8bc0 0000000000000001 ffff8800a1157be8 ffffffff8123a917
 0000000000000000 ffff8800a1157c40 ffffffff81745465 ffff8801d692e5a8
Call Trace:
 [<ffffffff81242fa2>] rcu_lockdep_current_cpu_online kernel/rcu/tree.c:1055 [inline]
 [<ffffffff81242fa2>] rcu_lockdep_current_cpu_online+0xf2/0x140 kernel/rcu/tree.c:1042
 [<ffffffff8123a917>] rcu_read_lock_sched_held+0x97/0x130 kernel/rcu/update.c:105
 [<ffffffff81745465>] trace_ext4_es_lookup_extent_exit include/trace/events/ext4.h:2384 [inline]
 [<ffffffff81745465>] ext4_es_lookup_extent+0x985/0xc30 fs/ext4/extents_status.c:835
 [<ffffffff8164b026>] ext4_map_blocks+0x156/0x16f0 fs/ext4/inode.c:492
 [<ffffffff81634dcb>] ext4_seek_data fs/ext4/file.c:576 [inline]
 [<ffffffff81634dcb>] ext4_llseek+0x68b/0x970 fs/ext4/file.c:717
 [<ffffffff81497af3>] vfs_llseek fs/read_write.c:260 [inline]
 [<ffffffff81497af3>] SYSC_lseek fs/read_write.c:285 [inline]
 [<ffffffff81497af3>] SyS_lseek+0x113/0x180 fs/read_write.c:276
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
Code: 00 00 8b 0d 95 6d ea 02 85 c9 75 18 65 8b 05 1a ce eb 7e 25 ff ff ff 7f 39 c3 7f 1b 81 fb fe 00 00 00 76 75 65 8b 05 02 ce eb 7e <f7> db 65 01 1d f9 cd eb 7e 5b 5d c3 e8 51 65 98 00 85 c0 74 f4